1. Field of Invention
This invention relates to intentional burning for land and forestry management and, in particular, to an aerial apparatus, method and system for dispensing incendiary spheres.
2. Description of Related Art
Prescribed burning is the intentional burning of typically forested areas or grasslands to meet specific land management objectives, such as to reduce flammable fuels, restore ecosystem health, recycle nutrients, or prepare an area for new trees or vegetation.
Some prior art devices for igniting prescribed fires include aerial ignition devices that are typically mounted within the cargo area of a helicopter and receive plastic spheres containing an incendiary material, such as potassium permanganate. The devices inject the received unprimed spheres with a reactant, such as ethylene glycol, to prime the incendiary spheres, and then expel the injected or primed incendiary spheres to fall from the helicopter. A delayed exothermic reaction between the incendiary material and the reactant within the spheres can produce a prescribed fire where the spheres land. The delay of the exothermic reaction is typically 25 to 30 seconds. An example of such prior art device is described in U.S. Pat. No. 8,776,693 that is incorporated herein by reference. Another prior art aerial ignition device dispenses incendiary capsules obtained from capsule belts stored in magazines, which also typically rely on an injection mechanism to inject reactant into the unprimed capsules. The aforementioned devices rely on a reciprocating injection mechanism on which a needle reciprocates in a linear manner. And most conventional aerial ignition devices are designed to be mounted in the helicopter with a chute extending to the outside and below the fuselage of the helicopter for dropping primed incendiary spheres or capsules on the ground below.
Mounting aerial ignition devices in the aircraft carries risks of onboard fires or smoke, and often involves obtaining onerous regulatory approval from governmental agencies that have oversight on aviation and aerial operations, for example the Federal Aviation Administration in the U.S. and Transport Canada in Canada. There are some ignition devices that are suspended below the helicopter but these are crude devices that rely on a gelled fuel mixture and an ignition source to drip flaming globules of fuel onto the ground below instead of incendiary spheres or capsules. The disadvantages of the gelled fuel dripping method include the hazards and inconvenience of transporting the fuel to the site, the hazards of hauling the gelled fuel in the air, the aircraft must return frequently to refill the gelled fuel, the method requires a larger and well trained crew, and the method does not lend itself to under-burning operation since the burning fuel globules can ignite tree crowns. Accordingly, there is a need for improved aerial ignition devices and methods.